Send the message between the brackets to the notifier message. All
reactions are returned in a list. The order in which the modules are
called is based on the priority of the module.

Here is an example of the use of map to insert footer navigation
items. This works as follows. When the template is rendered the
zotonic notifier is called with the message {footer_navigation,[{current_location=Id}]}. Zotonic modules can listen to this message
and return this information. This can be very handy if you have to
create dynamic interfaces based on what modules are enabled: